I think I may have solved it, but please feel free to disagree.
I took a punt and ordered the marriage certificate of Ernest Walter Reeves and Sarah Miriam Russ they married 05 Jan 1918 at Cardiff registry office. He was a Private age 23 in the South Lancashire Regiment, his address was 16 Station Road, her's was 14 Station Road (she was age 24). His father was Frank Reeves a farm Labourer, hers was Charles Robert Russ a Blacksmith.
I found Walter in 1901 and 1911 with his parents and siblings. His mother was an Emily Smith. In 1901 his brother Albert Reeves (Albert George Reeves) is with him born about 1892.
A copy of of Ernest’s birth certificate reveals his DOB as 15 Nov 1894. In 1939 it is given as 15 Nov 1893, I think there is a year error in 1939. The potential YOB correction in the 1939 register to 99 I believe is an error.
He possibly died in 1959 in Cardiff. I can’t find a death for Sarah Miriam